I have created two post types, events and registrations and would like to be able to loop through the events and then fetch the registrations for each event, but WP_Query seems not to be working.

The data is setup for 9 events and 3 registrations, two for one event and one for another

It seems to not fetch the registration data correctly.

            $events = new WP_Query(Array(
                'posts_per_page' => -1,
                'post_type' => 'event'
            ));
            if ($events->have_Posts()){
                while($events->have_posts()){
                    $events->the_post();
                    echo "<p>Event " . get_the_title() . '</p>';
                    $eventID = $events->get_the_ID();
                    echo $eventID;
                    $args = array(
                        'post_type' => 'registration',
                        'meta_key' => 'event_id',
                        'meta_value' => $eventID,
                        'meta_compare' => '='
                    );

                    $registrations = new WP_Query($args);
                    while ($registrations->have_posts()){
                        $registrations->the_post();
                        echo "<p>The registrations list "  . get_the_title() . "</p>";
                    }
                }
            }

I get the following results

Event 1
Event 2
Event 3
Event 4
Event 5
Event 6
Event 7
Event 8
Event 9

If I change the line 'meta_compare' => '=' to 'meta_compare' => '!=' I get the following

Event 1
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 2
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 3
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 4
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 5
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 6r Registration
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 7
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 8
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 9
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1

Not sure why this is proving to be so hard, maybe it's because they're both posts, just different types, from the same table.

Can anyone help please?

I have created two post types, events and registrations and would like to be able to loop through the events and then fetch the registrations for each event, but WP_Query seems not to be working.

The data is setup for 9 events and 3 registrations, two for one event and one for another

It seems to not fetch the registration data correctly.

            $events = new WP_Query(Array(
                'posts_per_page' => -1,
                'post_type' => 'event'
            ));
            if ($events->have_Posts()){
                while($events->have_posts()){
                    $events->the_post();
                    echo "<p>Event " . get_the_title() . '</p>';
                    $eventID = $events->get_the_ID();
                    echo $eventID;
                    $args = array(
                        'post_type' => 'registration',
                        'meta_key' => 'event_id',
                        'meta_value' => $eventID,
                        'meta_compare' => '='
                    );

                    $registrations = new WP_Query($args);
                    while ($registrations->have_posts()){
                        $registrations->the_post();
                        echo "<p>The registrations list "  . get_the_title() . "</p>";
                    }
                }
            }

I get the following results

Event 1
Event 2
Event 3
Event 4
Event 5
Event 6
Event 7
Event 8
Event 9

If I change the line 'meta_compare' => '=' to 'meta_compare' => '!=' I get the following

Event 1
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 2
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 3
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 4
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 5
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 6r Registration
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 7
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 8
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1
Event 9
The registrations list for Evnt 1
The registrations list for Evnt 2
The registrations list for Evnt 1

Not sure why this is proving to be so hard, maybe it's because they're both posts, just different types, from the same table.

Can anyone help please?

• php

2 Answers 2

As per WP documentation,

Using the WP_Meta_Query::parse_query_vars( $query ) method: You can use this method, if you want to use the simple query args(meta_key, meta_value, meta_type, meta_compare), or if you are unsure of the presence of meta query parameters.

Hence, I tried converting meta_key, meta_value and meta_compare in source code to wrap inside meta_query as key, value, compare.

Also, added if( $registrations->have_post() ) {

Can you check if below code snippet works for you ?

            $events = new WP_Query(Array(
                'posts_per_page' => -1,
                'post_type' => 'event'
            ));
            if ($events->have_posts()){
                while($events->have_posts()){
                    $events->the_post();
                    echo "<p>Event " . get_the_title() . '</p>';
                    $eventID = $events->get_the_ID();
                    echo $eventID;
                    $args = array(
                        'post_type' => 'registration',
                        'meta_query' => array (
                          'key' => 'event_id',
                          'value' => $eventID,
                          'compare' => '='
                        )
                    );

                    $registrations = new WP_Query($args);
                    if( $registrations->have_post() ) { 
                      while ($registrations->have_posts()){
                        $registrations->the_post();
                        echo "<p>The registrations list "  . get_the_title() . "</p>";
                      }
                    }
                }
            }

Edit 1 :

If the event_id is an ACF then you should try fetching registrations using ACF functions.

Ref: https://www.advancedcustomfields/resources/query-posts-custom-fields/

echo $eventID;
$registrations = get_posts(array(
   'numberposts'   => -1,
   'post_type'     => 'registration',
   'meta_query'    => array(
       array(
           'key'       => 'event_id',
           'value'     => $eventID,
           'compare'   => '=',
       ),
   ),
));

if( $registrations->have_post() ) { 
 while ($registrations->have_posts()){
   $registrations->the_post();
   echo "<p>The registrations list "  . get_the_title() . "</p>";
 }
}

I have managed to sort this with your help, thanks. I have still used WP_Query but the problem lay in the fact that the event_id is a relationship and therefore an array, so "=" as the meta_type wouldn't work Here is the working code.

            $events = new WP_Query(Array(
                'posts_per_page' => -1,
                'post_type' => 'event',
                'meta_key' => 'event_date',
                'orderby' => 'meta_value_num',
                'order' => 'ASC'
            ));
            if ($events->have_Posts()){
                while($events->have_posts()){
                    $events->the_post();
                    echo "<p>Event " . get_the_title() . ' ' . get_the_id() . '</p>';

                    $registrations = new WP_Query(Array(
                        'posts_per_page' => -1,
                        'post_type' => "registration",
                        'meta_key' => 'boat_type',
                        'orderby' => 'meta_value',
                        'order' => 'ASC',
                        'meta_query' => array(
                          array(
                              'key'=> 'event',
                              'compare' => 'LIKE',
                              'value' => '"' . get_the_ID() . '"'
                          )
                        )
                      ));
                      if ($registrations->have_posts()){
                          while ($registrations->have_posts()){
                              $registrations->the_post();
                            echo "<p>---------reg title is: " . get_the_title() . " and id is " . get_the_ID() . "</p>";
                          }
                      }
                }
            }

Now displays

Event 1
Event 2
---------reg title is: Manual Registration and id is 221
Event 3
Event 4
---------reg title is: Registration and id is 217
---------reg title is: Another Registration and id is 222
Event 5
Event 6
Event 7
Event 8
Event 9